What Are Zonemaps?

1.	What Are Zonemaps?
Answer» An extent is the smallest unit of disk allocation on a SPU. Zonemaps is internal mapping structures to the extents that take ADVANTAGE of the internal ORDERING of data to eliminate extents that do not need to be SCANNED. Zonemaps TRANSPARENTLY avoid scanning of unreferenced rows. Zonemaps are CREATED for every column in the table and contain the minimum and maximum values for every extent. An extent is the smallest unit of disk allocation on a SPU. Zonemaps is internal mapping structures to the extents that take advantage of the internal ordering of data to eliminate extents that do not need to be scanned. Zonemaps transparently avoid scanning of unreferenced rows. Zonemaps are created for every column in the table and contain the minimum and maximum values for every extent.

Answer»

An extent is the smallest unit of disk allocation on a SPU. Zonemaps is internal mapping structures to the extents that take ADVANTAGE of the internal ORDERING of data to eliminate extents that do not need to be SCANNED. Zonemaps TRANSPARENTLY avoid scanning of unreferenced rows. Zonemaps are CREATED for every column in the table and contain the minimum and maximum values for every extent.

An extent is the smallest unit of disk allocation on a SPU. Zonemaps is internal mapping structures to the extents that take advantage of the internal ordering of data to eliminate extents that do not need to be scanned. Zonemaps transparently avoid scanning of unreferenced rows. Zonemaps are created for every column in the table and contain the minimum and maximum values for every extent.

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